Mononuclear and polynuclear 5-coordinate zinc(II) model complexes: a quantum chemical calibration study of their structure and energy

• Published in: Structural chemistry 2013-12, Vol.24 (6), p.2089-2099
• Main Authors: Mayhan, Collin M., Szabo, Tamas J., Adams, John E., Deakyne, Carol A.
• Format: Article
• Language: English
• Subjects: Chemistry; Chemistry and Materials Science; Computer Applications in Chemistry; Original Research; Physical Chemistry; Theoretical and Computational Chemistry
• ISSN: 1040-0400; 1572-9001
• DOI: 10.1007/s11224-013-0346-6

To further our understanding of the properties of zinc-seamed pyrogallol[4]arene nanocapsules, we have investigated the energetic and geometric properties of the model complexes Zn(C 2 O 2 H 3 ) 2 Y, Y = NH 3 , C 5 H 5 N, CH 3 OH, (CH 3 ) 2 NCHO, or (CH 3 ) 2 SO, with a zinc coordination sphere representative of that in the capsules. The effect of the choice of density functional, basis set, and zinc pseudopotential on the equilibrium structures and Y ligand bond dissociation enthalpies has been assessed. Among the ways in which the suitability of these models has been confirmed was the construction of polynuclear zinc complexes having 2, 4, 6, or 8 metal ions combined with C 2 O 2 H 3 − , C 4 O 3 H 4 2− , and NH 3 ligands, which indeed show that a closed ring is formed. The natural curvature of these complexes suggests that pentacoordination of Zn may be a key factor in seaming the pre-existing cone-shaped pyrogallol[4]arenes to form dimer capsules.